Efficient structures help build a sustainable future

July 16, 2014

This is a cable structural system for Functional Unit 2 (3 bays or units). Credit: ASCE

When envisioning a new structure, engineers often have to balance design choices against the environmental impact of materials used. It is estimated that 40 to 50 percent of greenhouse gases are produced by the construction industry, according to the California Integrated Waste Management Board. Lessening the impact of construction on the environment is a work in progress.

Researchers at the University of Miami (UM) and the University of Milwaukee School of Engineering are searching for designs and materials that are less harmful to the environment. The team compared the sustainability of two structural systems commonly used for spans exceeding 250 feet: the steel cable system and the steel truss system.

"Thoughtful selection, by the architectural engineer, in the initial stages of the design process, can reduce environmental impact related to the construction process," says Matthew Trussoni, assistant professor in practice, at the UM College of Engineering and corresponding author of the study.

The findings show that the selection of steel cable structural system for long spans has considerably less environmental impact than a steel truss system to achieve the same structural requirements, through the entire life cycle of the structure.

Like a spider web, the cable system utilizes tension to sustain a structure. In contrast, the truss system uses compression members in the span of the structure.

This is a pratt truss structural system for Functional Unit 2 (3 bays or units). Credit: ASCE

"Most structures in nature rely on tension as it is the most efficient way to transfer forces," Trussoni says. "They typically minimize compression members and maximize tension members," he says. "In a tree, for instance, the trunk is the only compression member, and the braches and leaves rely on either a combination of tension and compression, or tension alone, for their support."

For the study, the researchers designed and compared the most efficient configurations for a steel truss and a steel cable structural system. Both systems were intended for the same function and with the same requirements.

To analyze the sustainability of each structure, they used the life-cycle-assessment (LCA), which estimates the environmental impact of a structure during material extraction, manufacturing, construction, use, maintenance and end-of-life phases.

The results show that the cable system has 29 percent less mass, 65.1 percent less embodied energy (the energy required to produce the structural system, including both materials and placement) and generates 67.2 percent less CO2 emissions, than the truss system.

The findings imply that understanding how material selection can affect efficiency is one way to mitigate environmental damage from construction.

The current study titled "Life-Cycle Assessment Comparison for Long-Span Cable and Truss Structural Systems: Case Study" was recently published in in the Journal of Architectural Engineering. Other authors are Evan Simatic, Christopher H. Raebel and H. Peter Huttelmaier, from the Milwaukee School of Engineering.

The researchers are continuing to investigate and compare environmental impacts of other structural systems that can serve the same purpose.

Related Stories

(PhysOrg.com) -- A team of structural engineers from the University of Sheffield in the UK say the assumptions originating with 17th century Dutch engineer Christiaan Huygens may need to be re-examined. Huygens assumed the ...

Exquisite buildings like the Eiffel Tower were made possible because of advances in structural engineering design methods. Truss structures, like the Eiffel Tower, are highly efficient; they can carry the same loads as solid ...

KIT researchers have developed microstructured lightweight construction materials of highest stability. Although their density is below that of water, their stability relative to their weight exceeds that of massive materials, ...

The construction industry could slash its carbon emissions by as much as 50% by optimising the design of new buildings, which currently use double the amount of steel and concrete required by safety codes.

US researchers have carried out an environmental lifecycle assessment of 2-megawatt wind turbines mooted for a large wind farm in the US Pacific Northwest. Writing in the International Journal of Sustainable Manufacturing, ...

Recommended for you

It sounds like a science-fiction nightmare. But "killer robots" have the likes of British scientist Stephen Hawking and Apple co-founder Steve Wozniak fretting, and warning they could fuel ethnic cleansing and an arms race.

A startup team calls their work a product. They also call it a social movement. Many people in the over-7,000 islands in the Philippines lack access to electricity .The startup would like to make a difference. Their main ...

Are some people fed up with remembering and using passwords and PINs to make it though the day? Those who have had enough would prefer to do without them. For mobile tasks that involve banking, though, it is obvious that ...